Yaro - Zika Virus Infection: Virology & Control

Zika Virus Infection : Virology & Control

Abubakar Yaro (Khalifa)

Content

Preface

Acknowledgement

Dedication

Chapter 1 Zika Virus: From the past to the present

Chapter 2 Zika Virus: Genomic Analysis & Replication

Chapter 3 Zika infection and innate immunity

Chapter 4 Autophagy and Zika virus

Chapter 5 Antiviral Development

Chapter 6 Antibody therapy for Zika Infection

Chapter 7 Zika Vaccine Development: Promises and Challenges

Chapter 8 Zika virus outbreak: Novel control strategies

Preface

What is this entire thing about Zika? Cant you scientists leave us alone? These were questions thrown at me by friend when he called me from Nigeria. I had read about Flavivirus but never showed interest in Zika virus till that call. I immediately mounted an intensive internet search and the headlines read like: Zika virus: First case reported in UK (BBC), Zika virus: outbreak likely to spread across Americas says WHO (BBC), Zika virus outbreak prompts CDC to expand travel advisory (Gizmodo), Rapid spread of Zika virus in the Americas raises alarm (Science News), and As Zika spreads, El Salvador asks women not to get pregnant until 2018 (Washington Post).The aim was avoiding birth defect associated with Zika viral infection. By then Zika virus was rising concern in the Americas with Brazil been the hardest hit. I later called my Nigerian friend to assure him that this was not a new virus but an emerging one that is on the rampage. This book will therefore outline some of the available data on Zika virus and make suggestions on how the world can deal with it and potentially draw ideas on how to deal with the menace of re-emerging infections. The book is divided into 8 chapters dealing with the history of Zika virus, structural and genomic analysis, life cycle, the effect of innate immunity and host responses to Zika infection, antiviral development, the prospect for vaccine development, antibody therapy, and novel control strategies. The book is a must read for Virologists, public health professionals and should be of interest to all medical libraries.

Acknowledgement

I have never stopped thanking my Maker for being a perfect guide to me and raising me from the brink of destruction to the level I am. My next thanks go to my parents for instilling in me the love for knowledge. To all my colleagues at Africa Health Research Organization thanks for being there for this wonderful project. Although we have not hit the level we should have, I am optimistic that with your level of commitment, nothing will stop us from playing a role in reducing diseases burden in Africa and beyond. I once had sisters who were willing to sacrifice their lives for me but death took them away. Sister Meri and Abiba, accept my biggest human thanks for been such wonderful sisters to me. Anytime I remember you, I shed tears. I miss you so much. My children brought out the best in me because by regarding me as the Super father, they place high responsibilities on me. That brought me to my senses and turned me into a working machine. Thanks kids for your love. I have so many scientific colleagues and mentors whose presence alone gave me the confidence that my pillars were strong so should not have any doubt. To all of you especially Virginia (South Africa), Prof Pranab (India), Prof Popejoy (USA), Prof Nadira (Sri Lanka) thanks so much. My wives Memuna Habibu Yaro and Ayishatu Haruna Yaro, you brought some much stability in my life. The once erratic Yaro has been replaced by a focused hardworking Yaro. I used only 30 days to complete this book. It is due to the peaceful tranquility you brought into my life. Thanks so much for your love! Finally to Winsome Morgan, I wouldnt be sitting by my study table by now had you not come into my life. Thanks so much for all the wonderful and beautiful things that you shared with me.

Dedication

This book is dedicated to my family

Chapter 1

Zika virus: From the past to the present

1.1 Introduction : On 18th April 1947, a rhesus monkey that had been placed in a cage on a tree platform in Zika forest of Uganda developed fever. The monkey called rhesus 766 was been used in Rockefeller Foundations program for research on yellow fever. Two days later, the monkey still febrile was taken to the foundations laboratory in Entebbe and its serum was inoculated into mice. After 10 days, all the mice that were inoculated intracerebrally became sick. A filterable transmissible agent that was to be called Zika virus (ZIKV) was isolated from the brains of the mouse. In the early part of 1948, ZIKV was isolated from Aedes africanus mosquito that was trapped in the same forest. Serological analysis showed that human could be infected. In 1968, ZIKV was isolated from human in Nigerian and during 1971 1975; a study showed that 40% of persons tested had neutralized antibodies to ZIKV. From 1951 through 1981, serological evidence of human ZIKV infection was reported from other African countries such as Uganda, Egypt, Tanzania, Sierra Leone, CAR, and Gabon. Other parts of Asia such as Malaysia, India, the Philippines, Thailand, Vietnam, and Indonesia also reported of the presence of ZIKV. Other studies also showed the presence of ZIKV in humans in Senegal, mosquitoes in Cote dIvoire, and in Ae aegypti mosquitoes in Malaysia. Olson et al reported that in 1981, seven people had serological evidence of ZIKV disease in Indonesia. A serological study showed that among 71 human volunteers, 9 had neutralizing antibody. In April 2007, an outbreak which was characterized by rash, arthralgia, and conjunctivitis was reported from the Yap Island in the Federated States of Micronesia. Serum samples from patients showed the presence of RNA of ZIKV.

Figure 1: Distribution of ZIKV, 1947-2007. The red circle showed outbreak in Yap Island, the yellow represents human serologic evidence, red indicates virus isolated from humans, and green are mosquito isolates (Source: Hayes, 2009).

A large outbreak was reported in French Polynesia in 2013-2014 where at least 396 laboratory-confirmed cases was reported and an estimated 29,000 people sought medical care for suspected Zika illness. The affected areas in the Pacific expanded to include the Cook Islands, New Caledonian, and Easter Island. The virus subsequently spread to several Oceania countries. Buathongs et al in 2013 reported of 7 cases of acute ZIKV infection in Thai resident from different regions of the country. The authors therefore suggested that based on the reported cases combined with previous ZIKV infection among travelers provided evidence that ZIKV is widespread across Thailand. On 7 th May 2015, the Pan America Health Organization (PAHO) issued an alert about potential ZIKV transmission in northeast Brazil. This was later confirmed with the wide spread of the disease. The World Health Organization (WHO) later suggested that at least 20 countries in the region including Bolivia, Guadeloupe, Guatemala, Puerto Rico, and Panama had all registered transmission of the virus. However the hardest hit was Brazil where about 1 million people contracted the virus. It was suggested that the presence of Aedes mosquitoes across Latin America, coupled with suitable climatic condition triggered the Zika epidemic in Brazil. Also viraemic travelers have been implicated in the introduction of the virus into at least 13 additional countries, where Aedes mosquitoes become infected and perpetuated local transmission cycle. Within 4 months, 4,000 potential cases of ZIKV-associated microcephaly in new born were reported. RNA of Zika virus has been detected in the amniotic fluid of affected newborns. This case of microcephaly led to the Deputy Health Minister of El Salvador Eduardo Espinoza to urge women to refrain from getting pregnant till 2018. This was after the country reported of its first case in November. Jamaica also gave similar suggestion. The US CDC on January 15 issued a travel alert urging women who are pregnant or who are trying to be pregnant to postpone travelling to countries where there was ongoing transmission of the virus (Figure 2). On 2 nd February 2016, the WHO declared ZIKV and its suspected complication in newborns constitute a public health emergency of international concern.